Serum Level of Vitamin D and Febrile Seizure? A Clinical Study

Objective: To evaluate the serum level of vitamin D in children aged six to 60 months with febrile seizure and febrile children without the seizure. Materials & Methods: Febrile children aged six to 60 months with or without seizure were studied. Demographic characteristics, serum level of vitamin D, and other laboratory findings were recorded. Results: Among the 104 children, 51 patients had fever without a seizure and 53 patients had a febrile seizure. The mean subjects’ age was significantly more in the febrile seizure group compared to the without seizure group (16.26 ± 11.87 versus 26.36 ± 14.11 months, p = 0.001). The mean serum level of vitamin D in the with and without seizure groups was 41.92 ± 22.42 and 48.41 ± 15.25 microgram per deciliter, respectively (p = 0.08). There was no significant correlation between serum level of vitamin D and seizure occurrence (p = 0.07). The mean serum sodium and potassium levels, and platelet count were significantly lower in the febrile seizure group compared to the without seizure group (p < 0.05). There were no significant differences between the two groups regarding hemoglobin, blood sugar, creatinine, blood urea nitrogen, calcium, alkaline phosphatase levels, and white blood cell count (p > 0.05). Conclusion: The serum level of vitamin D in febrile children with or without seizure was normal. The serum level of vitamin D was lower in patients with the seizure but not statistically significant. More clinical studies are needed to evaluate the relationship between febrile seizure and the serum level of vitamin D.


Introduction
Febrile seizure (FS) is one of the common childhood neurologic diseases that involves three to five percent of children (1,2). FS is recurrent in 30% of patients (3,4). Despite many proposed mechanisms, its exact pathogenesis is unknown.
Genetic and environmental factors are assumed to be involved in its mechanism (5). Seizures can be the outcome of several conditions stimulating the central nervous system (CNS) such as fever, electrolyte disturbances, some infections, head trauma, etc. (6,7).
Vitamin D deficiency is a prevalent public health problem throughout the world, particularly in developing countries. Vitamin D deficiency is more common during the rapid growth stages, such as infancy and adolescence (8). The prevalence of vitamin D deficiency and insufficiency in Iranian children is 16.1% and 25.2%, respectively (9). report studies (11)(12)(13)(14)(15).
The present study was designed to evaluate the relationship between serum level of vitamin D and FS in the children aged six to 60 months. Patients with a history of acute or chronic renal diseases, meningitis, febrile convulsion or epilepsy, head trauma, encephalitis, and brain hemorrhage were excluded.

Sample size
Sample size study populations of 104 patients were considered appropriate to achieve a reasonable statistical analysis.

Analysis
Statistical analysis was performed using SPSS windows program version 16 (SPSS Institute, Inc., Chicago, IL, USA). All quantitative variables were described as mean ± standard deviation (SD) and compared between the two groups by independent samples t-test or its nonparametric equivalent. The qualitative variables were compared between the two groups using Chi-square test. P-values less

Demographic characteristics
Among the 104 included children, 51 patients had fever without a seizure and 53 patients had a febrile seizure. In without seizure group, 24 cases (47.1%) were female and 27 cases (52.9%) were male with the mean age of 16.26 ± 11.87 months.
In the FS group, 26 cases (49.1%) were female and 27 cases (50.9%) were male with the mean age of 26.36 ± 14.11 months. There was no significant difference between the two groups regarding the subjects' gender (p = 0.999). The mean subjects' age was significantly more in the febrile seizure group compared to the without seizure group (p = 0.001, Table 1).
The mean body temperature was 38.85 ± 0.55 and 38.38 ± 1.97 0 C in with and without seizure groups, respectively (p = 0.13).
There were also no significant differences regarding the existence of underlying disease (p = 0.14), type of parturition (p = 0.999), and breastfeeding (p = 0.75) between the two groups.

Discussion
The serum vitamin D level of one-hundred four febrile patients with or without seizure was studied.
Although the serum level of vitamin D in patients with seizure was lower than the patients without the others. It may be due to the administration of vitamin D supplements in these patients. Vitamin D receptors broadly spread in the brain that affecting calcemic and non-calcemic actions (16).
The differences regarding serum levels of platelet, sodium, and potassium were significant between groups, but Hb, WBC, BS, Cr, BUN, Ca, and ALP was not.
The anticonvulsant nature of vitamin D initially was reported in 1974 (17). Vitamin D receptors exist widely in the brain, and vitamin D can act as a neurotransmitter. It also may enhance the effect of other neuroprotectin agents. It has been suggested that some metabolic changes may occur during febrile disease (16). To the best of our knowledge, there is no clinical study evaluating and comparing the serum level of vitamin D in febrile children with and without seizures.
In the present study, the serum level of vitamin D in both groups of with and without seizure was within the normal range, interestingly. The mean serum level of vitamin D in patients with seizures was lower than the patients without a seizure. In other reports, the low serum level of vitamin D in patients with seizures was reported frequently (6,11,12,14). It may be to some extent due to differences in the design of the study, dietary habits, and geographic situation. In a recent study in Iran on 40 children with seizures, it has been reported that only 20% of them had a sufficient serum vitamin D level (6). In another study in Iran, the prevalence of insufficient vitamin D was 46.6% (18).
In our study, the serum level of sodium was significantly lower in patients with seizures. It may be due to inappropriate secretion of anti-diuretic hormone (ADH). Also, the potassium level was lower in the case group. The actual reason is not